The Effect of a Ceramide-Containing Product on Stratum Corneum Lipid Levels in Dry Legs

April 2020 | Volume 19 | Issue 4 | Original Article | 372 | Copyright © April 2020


Published online March 12, 2020

Zoe D. Draelos , Nada H. Baalbaki , Shelby Cook , Susana Raab , Gene Colón

aDermatology Consulting Services, PLLC bL'Oréal Research and Innovation, Clark NJ cL'Oréal USA, Inc. (CeraVe), New York, NY





highly statistically significant improvement in skin dryness, skin texture/roughness (tactile), skin texture/roughness (visual), desquamation/flakiness, luminosity/radiance, and overall appearance of healthy skin comparing the treated leg to the untreated leg (P<.001; Figure 1). At the remaining time points, day 3 and week 4, highly statistically improvement was seen in all parameters assessed comparing the treated to the untreated leg (P<.001). This improvement was maintained during the 48-hour regression period in all parameters (P<.001). The investigator captured the improvement with photographs at each time point (Figure 2).

Subject Results
In the Subjective Sensory Assessment, the subjects were asked to assess itching, stinging, and burning at baseline, immediately following application, day 3, week 4, and 48-hour regression separately for each lower leg. Immediately following application, the subjects noted a statistically significant reduction in stinging (P=.008), burning (P=.001), and itching (P<.001) for the leg receiving the study product. This represented a 60% reduction in itching, 55% reduction in burning, and a 42% reduction in stinging. This improvement continued throughout the 4-week study and even into the 48-hour regression period.

D-Squame Lipid Results
After 4 weeks of moisturizer application, the D-Squame analysis revealed a 10% increase in total skin ceramide content comparing the treated to the untreated leg (Figure 3). In addition, there was a 10% increase in cholesterol levels and increase in free fatty acids levels. This reflects a significant increase (P<.01) in skin barrier lipid content at 4 weeks. This was maintained for the total skin ceramide content and cholesterol levels after discontinuation for 48 hours (P=.025).

DISCUSSION

Many ingredients are incorporated into moisturizer formulations for a variety of purposes. The studied moisturizer contained glycerin and hyaluronic acid to function as humectants to increase skin water content and dimethicone as an occlusive agent to maintain the increased water content in the skin. Emollients, such as caprylic/capric triglyceride, cetearyl alcohol, and ceteareth-20, were included to smooth rough skin created by improperly desquamating corneocytes. Most moisturizers contain ingredients to meet these basic formulation functions; however, the study moisturizer contained a variety of ingredients to bring additional skin barrier benefits. These included cholesterol, phytosphingosine, and ceramides 1, 3, and 6-II, which are all components of the intercellular barrier lipids. The phytosphingosine-containing ceramides utilized in the formulation are plant derived using a bio-fermentation process to produce skin-identical configurations. These ingredients are organized within a multivesicular emulsion (MVE) designed to time-release concentric spheres of oil and water into the skin. The MVE contains concentric spheres of moisturizing ingredients that are released onto the skin surface layer by layer to create the extended ingredient delivery mechanism.

Of the ingredients incorporated into the barrier lipids, ceramides are one of the most important in providing for the waterproof characteristics of the skin barrier. In order to prevent skin surface ceramide contamination, the top tape strip from all samplings was discarded and only the lower tape strips analyzed. This provided for documentation that the measured ceramides were actually present within the stratum corneum and not only onto the surface. The study moisturizer significantly increased skin barrier lipid levels after 4 weeks of regular use. This increase in total skin ceramide content was sustained even after moisturizer was discontinued for 48 hours.

Rather than running the study during the winter months with low ambient humidity, the study was run with daily rain from weeks 2 to 4, providing an opportunity to understand the ability of a moisturizer to increase skin water content despite high humidity conditions. The studied moisturizer increased skin hydration after only 3 days compared to the untreated leg. This improvement was maintained at week 4 and was still significant after the 48-hour regression phase. The increase in skin hydration was accompanied by a significant and sustained visual improvement in dry skin symptoms in the treated leg. Despite the high humidity and warmer temperatures during the study, the test product was very well perceived for both texture and